He said: "It's difficult to imagine how the European Union could function should such a Eurosceptic as Le Pen be at the helm of one if its major economies … It would likely precede its fracturing.”

It's difficult to imagine how the European Union could function should such a Eurosceptic as Le Pen be at the helm of one if its major economies … It would likely precede its fracturing

Michael Hessel

Mr Hessel predicted the Front National leader has a one in five chance of becoming president in France.

Sigmar Gabriel, Germany’s economy minister, also predicted the EU could fall if Ms Le Pen in France and far-right leader Geert Wilders succeeds in the Netherlands following the success of Brexit.

He told the German parliament: "After Brexit last year, if enemies of Europe manage again in the Netherlands or in France to get results then we face the threat that the largest civilization project of the 20th century, namely the European Union, could fall apart.”

Opinion polls suggest Ms Le Pen is likely to top the first round of the presidential poll

Opinion polls suggest Ms Le Pen is likely to top the first round of the presidential poll on April 23 but then lose the May 7 run-off to conservative Francois Fillon or centrist Emmanuel Macron.

But in a race that is turning out to be the most unpredictable France has known in decades, the Front National hopes this weekend's rally in Lyon, where Le Pen will spell out her electoral agenda, will help convince voters who have traditionally backed mainstream parties to give her a chance.

If Ms Le Pen wins the presidency and takes France out of the EU, Larissa Brunner, analyst for western Europe at think tank Oxford Analytica, told CNBC the bloc could become an economic union in a bid to avoid complete collapse with Italy possibly the next country to leave.

She said: "It is quite hard to quantify (Le Pen's) chances, but I would put them at around 10 percent – not impossible, but not very likely either.

GETTY

Polls suggest centrist Emmanuel Macron or Mr Fillon could win the May run-off

REUTERS

Ms Le Pen is up against conservative Francois Fillon

"Should Le Pen deliver 'Frexit', it could put the future of the EU into question. I don't think the EU would collapse – after all, there would still be 26 countries left – but without one of its key founding members it would lose global influence and could slowly disintegrate.

"It could even turn into a merely economic union and become more similar to the European Economic Area (EEA) or the customs union. Assuming a 'Frexit' goes smoothly, other countries such as Italy could follow.”

Get to know Marine Le Pen
Sat, January 28, 2017

Marine Le Pen is a French politician who is the president of the National Front, a national-conservative political party in France and one of its main political forces.

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A French politician who is the president of the National Front (FN), a national-conservative political party in France and one of its main political forces.

It comes as Spain’s Prime Minister Mariano Rajoy said he does not want to think of the possibility of the Front National leader winning the French presidential election this spring.

The Spanish prime minister warned Ms Le Pen could destroy Europe as politicians and commentators warned the far-right leader could deal a “severe blow” to the EU if she wins.

Mr Rajoy told local radio station Onda Cero: “It would simply mean the destruction of Europe.”